Has anyone else fitted an uprated lower pulley on the 4.2 engine? I see eurotoys do one and I’m slightly tempted.....

 

No but I have a top pulley installed. Any gains adding a bottom or will I be spinning too much?

 

Way too much since the top 10% pulley already does on its own.

 

Thanks for bringing this thinking back to life.
yes, when I get home +1 on the bottom pulley.
I did have it on the xjr. For passing purposes;-)

 

Currently, my charger is at Powerhouse being ported and having the upper pulley done. This is why I’m considering doing the lower one at the same time. It’s not done very often in the 4.2 engine it appears, which I guess is why I can only find the parts on eurotoys and would have to ship it to the uk.

The other thing, is with both pulley’s done you would definitely need meth/ water injection, as the intake temperatures will be Very high otherwise

 

Bigger crank pulley on a 4.2L is a complete waste of time & money.

I ended up putting the stock crank pulley back on my XKR after weeks of messing around modifying the engine tune to compensate for the loss of efficiency from the bigger pulley and getting nowhere near the promised gains, no gains at all actually.

Couple of thousand dollars on a pulley kit to not run any faster or quicker down the 1/4 mile.

The drive belt squealed as well, tried two different versions, belt grip spray, etc, in the end I put the stock pulley back on, no more noise, and same performance as with the pulley fitted.

Waste of time & money.

 

Cambo, do you mean my gains were strictly from the upper?

 

What gains?

 

That 10% supercharger pulley really heats things up enough as it is. I don't think our charge cooling system would handle the heat generated from both upper and lower pulleys unless you are running an ice tank (definitely not here in Florida). I have done that, and trust me it is not practical.

Meth might help mitigate the IAT's but then you have to play with a tedious tune like Cambo mentioned. And if he didn't tweak the parameters to make it work, I doubt you will find anyone else that will. +1 on not worth the time and money.

I really think you could invest the cost of that pulley into other mods and get more results.

 

What other mods can you recommend? I am already in the process of doing / have done:

Stage 2+ porting of charger
Meth
X-pipe
200 cell cats
Upper charger pulley
​​​​​​​Intercooler pump upgrade

 

LSD.

I have done all of the above however the LSD was by far the best mod I made.

​​​​​​​What is the point in having so much power if all you do is spin one wheel on take off.

 

I missed that off the list. That is something I am in the process of sorting, however need to find out how I can tell the difference between the original diff and the GKN unit, incase it was swapped over on mine. Knowing my luck, I would order the LSD to then find I have the GKN unit.

 

Yes I forgot. I read your post.

 

Remove and clean your intercoolers for sure. It won't add power, but it will restore power. You'll definitely notice difference after that. I made 14whp on the dyno more with just clean intercoolers, consistently too. Catch can would help maintain them (so will meth though).

Unrestrict your intake and exhaust a bit more-
Caldoofy j tube, and RR upper intake if you can get one.
The high flow cats will help if you don't melt them. But there are benefits to more free flowing exhaust.

​​​​​​​Otherwise, it's all about the maintenance... some nice spark plugs. Maybe a step cooler. Constantly check your oil and replace the pcv valve occasionally. And a can of Bg44k every once in a while.

 

+1 on the above.

I have a RR upper intake on order. Great price on Ebay.Got lucky with that.

That will probably be the last mod I will make to this car.

 

When you talk of the RR upper intake, is it the below you are referring to? If so how does this differ to the Jag part?


​​​​​​​

 

Yes that is it.

It is supposed to have a better air flow design than the original.

Several people have attested to that.

Mine should be delivered today so will examine closely and compare.

Picked it upon Ebay for a low price way below others that were listed.

This will be my last modification.

Lots of people have made intake modifications to improve air flow as you know however the main bottleneck is the right angled elbow beneath the TB going in to the SC so whatever you do prior to that you still have that issue even if you have a larger bore TB.

I polished and ported that elbow to match the inlet to the SC when I had it all off for cleaning.

 

You will be happy with it. It is massive compared to the original, its 90mm i believe. Not sure how effective the heat sinks are, but they do look cool

I dont think just this one mod would open up more power for anyone. But when you have it in conjunction with other intake and supercharger mods like you have it does make a difference, even without a tune.

 

I have just got one off ebay for £30, which seems very cheap indeed.

The elbow below the TB is being ported at the moment along with the charger

 

Thats a very good price.